If you are using the new Guttenberg version of wordpress and are having some issues with the Flixel Embeds then I will show you how to get them to work.
Choose the code block as there is no longer a different editor.
Change the block type to “preformatted” and your cinemagraph should appear. You have to do this in this particular order. If you simply select the preformatted block, your code will be visible.
After selecting to transform the block type to preformatted, your embed should appear.